Cable logging uses a yarder and cables to remove logs from inaccessible areas. High potential and skyline logging are common methods. The yarder can be mounted on a sled, trailer, or tracked vehicle. Cables stabilize the yarder and are used to transport logs. High lead wire logging and skyline logging involve descending carriages to retrieve logs. Swing yarders use grappling hooks to lift and transport logs.
A necessary aspect of some logging industries, cable logging uses a yarder and numerous cables, chains and grapples, in a variety of configurations, to remove logs from areas that are too steep or otherwise inaccessible to loaders and trucks. Two of the more common cable logging methods include high potential logging and skyline logging. Both techniques use cables, suspended over a job site, on which pieces of equipment travel, retrieve logs, and return to the desired location. Once the logs arrive at an accessible location, loaders stack the felled trees onto trucks for transport.
The yarder, which is the primary piece of equipment used in cable logging, can be mounted on a sled, trailer, or very large motorized tracked vehicle. Cable gauges have a tall mast, or spar, and numerous cables run the length of the spar to the top, where they are threaded through a circular support and extended outward. On a tracked vehicle, these cables are usually held on drums or large mechanical reels. A swing yarder, also known as a grapple yarder, generally has an extendable rotating arm with pulleys at the end, through which the cables run.
Most of the cables extending from the top of the spar stabilize the yarder. Loggers connect the ends of the cables to large logs located around the periphery of the construction site. The cables used for logging lines can run from construction site to construction site, across a valley, or from construction site to tree along the side of a mountain. Mechanical, motorized, or self-propelled carts travel the length of logging wires and have a fixture that bolts to or around logs.
High lead wire logging usually involves a type of dolly with hooked vertical chains that extend downward. The carriage descends along the cable until it reaches the desired position. Once the dolly is in place, loggers wrap the dangling chains around the logs, securing each chain with a hook. The cart rises and carries or drags the logs to another location along the wire.
Skyline recording involves a similar principle but generally involves much higher wires. The carriage descends, the workers attach the logs to the fixture, and the line suspends the logs in the air. The trolley then travels along the wire to the desired location. Swing yarders usually have mechanical grappling hooks in place of carts that traverse the logging wire, lift individual logs, and haul them from one area to another.
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